Method and clamping apparatus for external fixation and stabilization

ABSTRACT

Clamping devices and methods for external fixation systems include a post component having a yaw axis and a clamping system secured to the post component and rotatable about the yaw axis. The clamping system includes a outer jaw and a inner jaw having an inner surface facing the outer jaw. The outer and inner jaws together form an opening for receiving a fixation element of the external fixation system. The inner jaw and outer jaw have a roll axis alignable with a longitudinal axis of the fixation element. The clamping system and post component are rotatable about the roll axis. The inner jaw also includes a cylindrical outer-facing surface. The devices also include a base component having a cylindrical concave surface having a pitch axis. The concave surface of the base component interfaces with the cylindrical outer facing component on the inner jaw. The outer and inner jaws being rotatable relative to the base and the post component about the pitch axis.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority to U.S.application Ser. No. 12/238.532, filed Sep. 26, 2008, and claims thebenefit of U.S. Provisional Application No. 60/995,535, entitled “Methodand Apparatus for External Fixation and Stabilization,” filed Sep. 27,2007, both applications being incorporated herein by reference in theirentirety.

BACKGROUND

Proper stabilization and reduction of a fracture using an externalfixation system requires proper alignment of the bone fragments. Suchalignment requires a fixation component that securely joins the pins andwires to the bars, but that is readily adjustable. Conventional fixationcomponents require a surgeon to clamp or lock the pins or wires to thebars, and if any adjustment is required during subsequent pin and barplacement, the surgeon must loosen the fixation component adjust it, andretighten the fixation component. This becomes tedious when complexfixation systems are required because surgeons spend inordinate amountsof time loosening, adjusting, and retightening fixation components.Further, such connections typically require two hands.

Some fixation components achieve mobility for case of placement usingjoints connecting two clamps. Most systems only provide a revolutejoint, the axis of which is perpendicular to both the pin and bar axes.Some systems replace the revolute joint with a ball joint allowing forroll pitch and yaw within some limited cone angle. This ball joint doescome at an expense though, namely an increase in the pin to barcenterline distance which increases the working envelope and increasesthe moment arm subjecting the clamp device to increased moment loadingnecessitating a larger device.

The present invention overcomes one or more disadvantages of the priorart.

SUMMARY

In one exemplary aspect the present disclosure is directed to a clampingdevice for an external fixation system. The device includes, a firstclamping system, a second clamping system, and a post componentextending into the first and second clamping system. In someembodiments, the first clamping system includes a first outer jaw and afirst inner jaw having an inner surface facing the outer jaw. The outerand inner jaws together forming an opening for receiving a firstfixation element of the external fixation system. The first clampingsystem also includes a first base component having a concave surfaceinterfacing with the first inner jaw and an opposing bottom facingsurface. In some embodiments, the second clamping system includes asecond outer jaw and a second inner jaw having an inner surface facingthe second outer jaw. The second outer and second inner jaws togetherform a second opening for receiving a second fixation element of theexternal fixation system. The second clamping system includes a secondbase component having a concave surface interfacing with the secondinner jaw and an opposing bottom facing surface. The concave surface ofthe first base component faces away from the concave surface of thesecond base component. The opposing bottom facing surface of the firstcomponent is in selective engagement with the opposing bottom facingsurface of the second component. In some embodiments, the concavesurface is a cylindrical surface.

In another exemplary aspect, the present disclosure is directed to aclamping device for an external fixation system. The device includes apost component having a yaw axis and a first clamping system secured tothe post component and rotatable about the yaw axis. The first clampingsystem includes a first outer jaw and a first inner jaw having an innersurface facing the outer jaw. The outer and inner jaws together form anopening for receiving a first fixation element of the external fixationsystem. The first inner jaw and first outer jaw have a roll axisalignable with a longitudinal axis of the fixation element. The clampingsystem and post component are rotatable about the roll axis. The firstinner jaw also has a cylindrical outer-facing surface. The deviceincludes a first base component having a cylindrical concave surfacehaving a pitch axis. The concave surface of the first base componentinterfaces with the cylindrical outer facing component on the inner jaw.The first outer and inner jaws are rotatable relative to the base andthe post component about the pitch axis.

In another exemplary aspect, the present disclosure is directed to amethod of building an external fixation system for stabilizing andreducing a bone. The method includes arranging a clamping device to bein an open bar-receiving condition by manually displacing a releaseelement toward a rear portion of outer and inner jaw components of theclamping device. A fixation element is inserted into an opening betweentransverse grooves formed in the outer and inner jaw components. Therelease element is displaced toward a front end of the outer and innerjaws so that the release element applies loading to the outer jaw torotate the outer jaw relative to the inner jaw and reduce the size ofthe opening between the transverse grooves formed in the outer and innerjaw components to place the clamping device in a provisionally lockedstate. The method also includes manipulating the clamping devicerelative to the fixation element. This includes pivoting the outer andinner jaws about an axis of a cylindrical concave surface on a basecomponent, pivoting the clamping device about an axis of a postcomponent extending through the clamping device, and rotating theclamping device about an axis of the fixation element. A locking elementis tightened on the post component to compressively lock the outer andinner jaws in position relative to the post component and the basecomponent.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an illustration of an exemplary external fixation systemaccording to one embodiment of the present disclosure.

FIG. 2 is an illustration of a perspective view of a clamping deviceaccording to one exemplary embodiment of the present disclosure.

FIG. 3 is an illustration of a side view of the clamping deviceaccording to the exemplary embodiment in FIG. 2.

FIG. 4 is an illustration of a cross-sectional view along lines 4-4 inFIG. 3.

FIG. 5 is an illustration of a cross-sectional view along lines 5-5 inFIG. 3.

FIGS. 6A and 6B are illustrations of an exemplary saddle according tothe exemplary embodiment of FIG. 2.

FIGS. 7A-D are illustrations of an exemplary inner jaw according to theexemplary embodiment of FIG. 2.

FIGS. 8A-D are illustrations of an exemplary outer jaw according to theexemplary embodiment of FIG. 2.

FIG. 9 is an illustration of a perspective view of a release leveraccording to the exemplary embodiment in FIG. 2.

FIGS. 10A-C are a series of illustrations showing the clamping device ofFIG. 2 changing from an open or bar-receiving condition to aprovisionally locked condition.

FIG. 11 is an illustration of a partial cross-sectional view of aclamping device according to one exemplary embodiment of the presentdisclosure.

FIG. 12 is an illustration of a perspective view of an exemplaryclamping component making up a portion of the clamping device accordingto the exemplary embodiment in FIG. 11.

FIG. 13 is an illustration of a side view of an exemplary clampingcomponent making up a portion of the clamping device according to theexemplary embodiment in FIG. 11.

FIG. 14 is an illustration of a back view of an exemplary clampingcomponent making up a portion of the clamping device according to theexemplary embodiment in FIG. 11.

FIG. 15 is an illustration of a perspective view of an exemplary sleeveforming a portion of the clamping device according to the exemplaryembodiment in FIG. 11.

FIG. 16 is an illustration of a partial cross-sectional view of anexemplary clamping component making up a portion of the clamping deviceaccording to another exemplary embodiment of the device in FIG. 11.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of various embodiments.Specific examples of components and arrangements are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting. In addition, the present disclosuremay repeat reference numerals and/or letters in the various examples.This repetition is for the purpose of simplicity and clarity and doesnot in itself dictate a relationship between the various embodimentsand/or configurations discussed.

The clamping systems disclosed herein combine desirable features of arelatively low profile with a high number of degrees of freedom. Theembodiments shown each include two similar clamps connected by a bindingpost. Manipulation of the clamps permits relative movement in a roll,pitch, and yaw direction, all the while maintaining a relatively lowprofile.

In addition, some embodiments of the clamping systems operate through arange of three positions, including open, provisionally locked, andlocked. The provisionally locked position connects the clamp to a bar orpin, but is still loose enough to permit post-placement manipulation.When the frame is in the desired arrangement, the clamp can be locked toresist further movement. In some embodiments, introducing the bar to theclamp triggers the clamp to move from the open position to theprovisionally locked position. This enables surgeons to more easilyassemble the external frame, and may permit one-hand provisionallocking, both simplifying and speeding the frame orientation process.

FIG. 1 shows an external fixation system 10 attached to a patient'sfractured tibia. The system 10 includes a rigid bar 12 and plurality ofpins 14 drilled into the bone on opposing sides of the fracture. Aclamping device 100 connects each pin 14 to the bar for rigid fixationand traction. Each pin 14 is received into a clamping device 100 byinserting the pin 114 between open top and bottom jaws of a fixatorclamp of the clamping device 100. In some embodiments, inserting the pin14 triggers the fixator clamp to change from an open position to aprovisionally locked position about the pin 14. In this position, thefixator clamp can be rotated about the pin, be axially displaced alongthe pin, or may pitch about the up or down around the cylindrical axisof the base element, but the jaws maintain the pin in the clamp. Oncethe pins 14 are set, the bar 12 is introduced into another fixator clampon the clamping device 100, forming a frame for the system. In someembodiments, as with the pins 14, inserting the bar 12 triggers thefixator clamp to change from an open position to a provisionally lockedposition. As remaining pins 14 are connected to the bar 12 using theclamping device 100, the fixation components may be adjusted to provideangulation and orientation necessary to align the bone for healing.Additional bar-to-bar fixation components and/or bar-to-pin fixationcomponents may be added to expand and connect the frame as required.Once properly created, the frame may be locked by changing the clampfrom the provisionally locked condition to the locked condition.

FIGS. 2 and 3 show an exemplary embodiment of a clamping device 100according to one aspect of the present disclosure. The clamping device100 includes a top fixator clamp 102 connected to a bottom fixator clamp104. Each fixator clamp independently receives and secures a bar or pin,or alternatively, can be used to fixate bars to bars. In otherembodiments, a single clamp can be used to fixate either a pin or a barto some other apparatus such as a ring or monolateral external fixationand/or deformity correction device. The clamp mechanism whether usedsingly or in pairs operates the same as each half is independent of oneanother. In some embodiments, the clamps are substantially identical,while in other embodiments, the clamps are substantially similar, buthave components sized or otherwise arranged to receive and securedifferent sized bars. In yet other embodiments, the clamping device 100includes only a single clamp 102, 104, with an alternative arrangementin place of the other clamp 102, 104. Since bars and pins may beinterchangeably held by either of the clamps 102, 104, as referred toherein, the use of the term bar is intended to mean any elongatestructure, including rods, shafts, pins, wires or otherwise, that extendfrom bones to the clamping device 100 or from other bars to the clampingdevice 100.

For convenience in FIGS. 2-5, similar components are labeled with thesame reference number, but are distinguished by a suffix, with thesuffix “a” identifying components of the first or top clamp 102 and thesuffix “b” identifying components of the bottom or second clamp 104.

Referring now to FIG. 2, The clamps 102, 104 each include a saddle base106, an inner jaw 108, and an outer jaw 110. A release lever 112operates to open the clamps 102, 104 and provisionally lock the clamps102, 104 upon receipt of a bar.

Each clamp 102, 104 of the clamping device 100 provides multiple degreesof freedom. FIG. 2 shows the degrees of freedom as a roll axis 150, apitch axis 152, and a yaw axis 154 in the upper and lower clamps 102,104. The roll axis 150 is the axis of a bar within the clamps and aboutwhich the clamping device 100 rotates. The pitch axis 152 is the axisabout which the outer and inner jaws rotate relative to the saddle base106 and relative to the opposing clamp. The yaw axis 154 is defined by abinding post (described below) and about which one of clamps 102, 104can rotate relative to the other.

FIGS. 4 and 5 are cross-sectional views along lines 4-4 and 5-5respectively showing inner features and components of the clampingdevice 100. Referring first to FIG. 4, the clamping device 100 includesa binding post 114 having spherical washers 116 and nuts 118 at eachend. This binding post 114 passes through both the clamps 102, 104 andacts to hold the clamps together. Between the clamps 102, 104, a wavespring 120 provides a biasing force to space the clamps 102, 104 apart,enabling easy, independent rotation of the clamps 102, 104 about thebinding post 114. This spring and its interaction with the saddle bases106 of each of the clamps 102, 104 will be discussed further below.

Each clamp 102, 104 of the clamping device 100 includes biasing wiresprings 120 (only one shown in FIG. 5), a torsion spring 124, and a pin126 which pivotally connects the inner jaw 108 to the release lever 112.The biasing wire springs 122 lie between and interact with the inner andouter jaws 108, 110 of the clamp 102 to bias the jaws toward an open orbar-receiving position. The torsion spring 124 operates between theinner jaw 108 and the release lever 112 to bias the release lever 112toward a locked position.

As will become apparent upon further reading, the release lever 112 maybe rotated out of locking engagement with the outer jaw 110, at whichtime the wire spring 122 will bias the outer jaw 110 away from the innerjaw 108, thereby opening the jaws to receive a bar. When a bar isintroduced between the outer and inner jaws 110, 108 with sufficientforce, the bar displaces the outer jaw 110, which releases the releaselever 112. The torsion spring 124 biases the release lever 112 into alocking engagement with the outer jaw 110, overcoming the biasing forceof the wire spring 122, and forcing the outer jaw 110 to pivot towardthe inner jaw 108 to provisionally lock or secure the bar between theinner and outer jaws 108, 110. In a provisionally locked state, asurgeon can still 1) rotate the clamping device 100 about the roll axis150 or slide the clamping device 100 axially along the bar to furthermanipulate the bars to a desired position in a roll direction, 2) rotatethe clamps 102, 104 of the clamping device 100 relative to each otherabout the yaw axis 154 and the binding post 114 in a yaw direction, and3) rotate the inner jaw 108 of each clamp 102, 104 about the pitch axis152 relative to the respective saddle base 106 to pivot the clamps 102,104 in a pitch direction. Once the frame is in place, with the barsoriented in the desired directions, the surgeon can lock the clampingdevice 100 to the bars by tightening one or both nuts 118 on the bindingpost 114.

In other embodiments, a snap ring or other element or collar is securedat the center of the binding post 114 to allow for independent lockingof either of clamps 102, 104. This snap ring allows for the locking of asingle base element to the lower jaw and locking the jaw rather thanlocking both clamps at the same time. In some embodiments, the collar isan integral part of the binding post 114.

FIGS. 6A and 6B show an exemplary saddle base 106 of each clamp 102,104. The saddle base includes an inner side 200, a concave outer-facingside 202, and a cylindrically shaped side wall 204 extending between theinner and outer-facing sides 200, 202. A central bore 206 extendsthrough the saddle base 106 from the inner side 200 to the outer-facingside 202. This central bore 206 is sized to receive the binding post114, as shown in FIG. 4, with enough clearance for the saddle base 106to rotate about the binding post 114 and the yaw axis 154 to providerotation in the yaw direction. In some embodiments, the central bore 206is shaped to limit or restrict rotation about the binding post 114. Forexample, the binding post 114 may have a non-circular cross-section andthe central bore 206 may be shaped to match the non-circularcross-section in a way that either limits or prohibits rotation aboutthe binding post 114.

The inner side 200 includes a central circular-shaped surface 208 and astepped shoulder 210. The central circular shaped surface 208 extendsaround the bore 206 and includes a circular array of radially extendingsplines that act to mate with the corresponding splines on the saddlebase of the opposing clamp or on some other foundation if used withoutan opposing clamp. In some embodiments, the splines resemble those on apoker chip and provide positive retention from planar rotation when thefaces are clamped together.

The stepped shoulder 210 on the inner side 200 extends about the centralcircular shaped surface 208 to the side wall 204 of the saddle base 106and provides a seat for the wave spring 120 (FIG. 4). In use, and asshown in FIG. 4, the wave spring 120 interfaces with the steppedshoulder 210 of the saddle base 106 of each respective clamps 102, 104.The wave spring 120 biases the opposing shoulders 210 of each saddlebase 106 apart, so that the radial splines on the opposing centralcircular shaped surfaces 208 are disengaged. Accordingly, the saddlebases 106, and therefore the clamps 102, 104, can rotate about thebinding post 114 relative to each other. However, the wave spring 120and the saddle shoulder 210 are sized so that upon tightening of the nut118, the wave spring 120 can be compressed to lie along the shoulder 210and the radial splines on the central circular shaped surfaces 208 ofthe opposing saddle bases 106 can engage to lock the clamps 102, 104from pivoting relative to each other.

The concave outer-facing side 202 of saddle base 106 includes parallel,longitudinal splines configured to interdigitate with correspondingsplines on the inner jaw 108. The concave outer-facing side 202 forms aradius about a saddle surface axis, about which the inner jaw 108 pivotsas it interfaces with the saddle base 106. During this process, thesaddle base 106 may displace relative to the inner jaw 108 against thewave spring 120 to alternatingly engage and disengage the splines,permitting the saddle base 106 or the inner jaw 108 to rotate relativeto one another about the pitch axis 152 in FIG. 2. It should be notedthat the angle of the longitudinal splines are such that they can bedisengaged by radial displacement, and do not require longitudinaldisplacement to disengage due to any keystone effect.

FIGS. 7A-D show the inner jaw 108. The inner jaw 108, cooperating withthe outer jaw 110, directly interfaces with the bar to secure the bar inplace. The inner jaw 108 includes an inner clamp face 240 facing towardthe outer jaw 110 and an outer clamp surface 241 that interfaces withthe saddle base 106. The inner clamp face 240 includes a transversegroove 242 for receiving a bar, a main surface 244 having a central bore246 and bias member grooves 248, and a pivot portion 250. The transversegroove 242 is located at a front end 249 of the inner jaw 108 and thepivot portion 250 lies at the opposite rear end 254 of the main surface244.

As shown in FIG. 7A, the transverse groove 242 extends from one lateralside to another and is shaped to receive a bar, pin, or other fixationor stabilization component. The transverse groove 242 is formed betweena hook portion 256 at the front end of the clamp that secures a bar inthe clamp. The transverse groove 242 may be formed with a rounded bottomportion or may be formed of a series of flats or faces. Some embodimentsmay have a combination of both curves and faces. The depth of thetransverse groove 242 may vary between different clamps, such as the topclamp 102 and the bottom clamp 104, depending on the size of the barintended to be gripped by the respective clamp. In some embodiments, theconfiguration and depth of the groove 242 may be configured to secure asmaller diameter bar, such as a bone pin or may be configured to securea larger diameter bar, such as a frame bar. Further, in someembodiments, because the cross-section of the bars and pins may haveshapes other than circular, the groove 242 may be shaped to alsomatingly interface with these bars and pins. For example, the groove 242may include teeth, cut-outs, or other features that interface with barshaving a non-smooth or non-circular outer surface.

The central bore 246 is a transversely extending opening having agenerally rectangular shape with a width and a length and the lengthbeing longer than the width. In the embodiment shown, the central bore246 has rounded or arching ends separated by substantially parallel sideedges spaced by the width. As best seen in FIG. 7C, the bore iscylindrical or conical-shaped at its ends 252 such that the bore lengthincreases as the bore depth approaches the outer clamp surface 241. Incontrast, bore sidewalls 254 are substantially parallel to each other,maintaining the bore width substantially constant. The binding post 114fits within the central bore 246 as shown in FIG. 4, and provides onlylimited movement relative to the post 114 in the longitudinal, or widthdirection. However, because the bore length is greater than the borewidth, the inner jaw 108 may move relative to the binding post 114substantially more in the transverse, or length direction, to change thepitch of the inner jaw 108 relative to the post 114. This length is theresult of a subtended arc who's vertex is coincident with the axis ofthe cylindrical surface ate ends 252.

This ultimately changes the pitch of the inner jaw 108 relative to thesaddle base 106. In the embodiment shown, the inner jaw 108 pivotsrelative to the saddle base 20 degrees in each direction, giving a pivotrange of 40 degrees. However, it should be apparent that in otherembodiments, the range of pivot articulation may be greater or less than40 degrees, and may be affected by the diameter of the binding post 114,the length of the central bore 246, as well as the angle of the boreends 252.

In the embodiment shown, the two bias member grooves 248 in the mainsurface 244 extend from the transverse groove 242 rearwardly toward thepivot portion 250. These two bias member grooves 248 receive the wiresprings 122 (FIG. 5) that operate to bias the inner jaw 108 and theouter jaw 110 to a closed position. The grooves 248 in the embodimentshown are parallel to each other, and have a decreasing depth from thetransverse groove 242 toward the pivot portion 250, ultimately endingwhere the bias member grooves 248 meet the main surface 244.

Referring to FIGS. 7A and 7D, the pivot portion 250 includes acylindrical passage 258 that receives the pin 126 (FIG. 5) andcooperates with the release lever 112 in the form of a hinge. In thisembodiment, the pivot portion 250 includes two connectors 260 separatedby a centrally located gap 262. This gap 262 is sized to receive thetorsion spring 124 (FIG. 5), as will be discussed further below.

The outer clamp surface 241 is a semi-cylindrical shaped surface thatincludes parallel, longitudinal splines shown in FIGS. 7C and 7D. Theseare configured to interdigitate with the corresponding splines on thesaddle outer facing side 202 shown in FIG. 6B. The cylindrical shapedsurface defines a radius r about which the inner jaw 108 pivots toprovide the range of motion. Naturally, pivoting only occurs when theinner jaw 108 and the saddle base 106 are spaced so that the splines arenot engaged. This may occur, for example, by displacing the saddle basetowards the wave spring or in some embodiments.

FIGS. 8A-8D show the outer jaw 110 in greater detail. The outer jaw 110includes a front end 272, a rear end 274, an inner clamp face 276, andan outer clamp surface 278. The inner clamp face 276 includes abar-receiving transverse groove 280 adjacent the front end 272, acentral bore 282, and bias member grooves 285. Similar to the groove 242on the inner jaw 108 described above, the transverse groove 280 extendsfrom one lateral side to another and is shaped to cooperate with theinner jaw 108 to receive a bar, pin or other fixation or stabilizationcomponent.

A hook portion 282 at the front end 272 defines a first portion of thetransverse groove 280 and, as shown in the cross-section of FIG. 4,aligns with the inner jaw hook portion 256 to define an opening throughwhich the bar may be introduced. Like the transverse groove 242discussed above, the transverse groove 280 may be formed with a roundedbottom portion, flats, faces, or some combination of both. In someembodiments, the depth and shape of the groove 280 is the same as thedepth and shape of the groove 248. Accordingly, the discussion aboverelating to the transverse groove 248 is equally applicable to thetransverse groove 280.

The central bore 282 includes features that enable it to providearticulation relative to the binding post 114 in a manner that the outerjaw articulation matches that of the inner jaw 108. FIGS. 8C and 8D showthe outer jaw 110 in cross-section and, along with the views in FIGS. 8Aand 83, provide an indication of the multiple surface aspects of oneexemplary central bore 282.

Referring to FIGS. 8B-D, the central bore 282 is generally hour-glassshaped, with a narrowing neck 286 located between the inner clamp face276 and the outer clamp surface 278. At the inner clamp face 276, thecentral bore 282 is relatively rectangular shaped with a width and alength, the length being greater than the width. From the inner clampface 276, the bore tapers inwardly toward the neck 286, with the innerbore surfaces including curved portions as well as planar portions. Asdiscussed further below, the central bore portion between the neck 286and the inner clamp face 276 is arranged and shaped to permitarticulation relative to the binding post 114 in a manner to matcharticulation of the inner jaw 108 so that during articulation, the innerclamp face 276 of the outer jaw 110 faces the inner clamp face 240 ofthe inner jaw 108. Accordingly, in the embodiment shown the central bore282 is sized to permit pivot rotation in the lateral direction of theouter jaw 110 within, for example, a pivot range of 40 degrees, matchingthat of the inner jaw 108. As discussed above, other pivot ranges arecontemplated and considered to be within the scope of this disclosure.Unlike the exemplary inner jaw 108, however, the outer jaw 110 in thisembodiment is configured to also provide articulation in thelongitudinal direction or front-to-rear direction. Accordingly as shownin FIG. 8D, the longitudinal direction also includes side walls taperingfrom the neck toward the inner clamp face 276. These inner clamp facesare not symmetrically disposed, but permit more articulation in onelongitudinal direction than the other. In the exemplary embodiment shownin FIG. 8D, for example, the inner clamp surface permits articulationfrom a center point in one direction of twenty degrees, and in the otherdirection, about 8 degrees. Accordingly, the outer jaw 110 is configuredto pivot in the longitudinal direction relative to the binding post 114up to about 28 degrees. Of course other articulation ranges are withinthe scope of this disclosure. The different angles, curved, and flatsurfaces can be seen in FIGS. 8B-D.

The central bore portion between the neck 286 and the outer clampsurface 278 is arranged and shaped to permit articulation relative tothe binding post 114 in a manner that permits the inner clamp surface278 to pivot and face the inner clamp surface 240 of the inner jaw 108.Here, the central bore 282 widens from the neck 286 toward the outerclamp surface 278. As can be seen in FIG. 8D, the central bore portionbetween the neck 286 and the outer clamp surface 278 is nonsymmetrical.In addition, the inner walls are formed with concave curves 287 near theneck 286. These curves 287 are shaped to interface with the sphericalwasher 116 in FIG. 4 and provide an articulation surface for the outerjaw 110 to articulate relative to the spherical washer 116 as the outerjaw 110 displaces to open and close the clamp 102.

In use, the outer jaw 110 displaces relative to the binding post 114 inthe lateral direction as the inner jaw 108 pivots with respect to thesaddle base 106. In addition, the outer jaw 110 displaces relative tothe inner jaw 108 to open the jaws to receive a bar into the transversegroove 280. This displacement is in the longitudinal direction, and usshown in FIGS. 4 and 8, the neck 286 of the central bore is shaped largeenough to permit pivoting about the center of the concave curveslongitudinally as well as laterally.

As shown in FIGS. 8B and 8C, the bias member grooves 285 extendlongitudinally on each side of the central bore 282. These groovesextend from the transverse groove 280 rearwardly toward the rear end 274and are sized and located to align with the bias member grooves 248 onthe inner jaw 108. Together the bias member grooves 285 on the outer jaw110 and the bias member grooves 248 on the inner jaw 108 receive thewire springs 122 (FIG. 5) which act between the two jaws 108, 110 tobias the outer jaw to an open, bar-receiving position. These grooves 285on the outer jaw 110 include a securing feature 288 formed as aninwardly extending indentation shaped to receive an end of the wiresprings 122, as shown in FIG. 5.

Referring now to FIG. 8D, the rear end 274 of the outer jaw 110 includesa locking interface 290 shaped to contact the release lever 112 tosecure the outer jaw 110 in the open position, and shaped to release theouter jaw 110 to close to the provisionally locked position. Thislocking interface 290 extends obliquely relative to the inner clamp face276 and the outer clamp surface 278 and includes a protruding edge 292that acts as a catch for the release lever 112 when the clamp 102 is inthe open position. Although shaped as a protrusion, in some embodiments,the edge 292 is an indentation or other catch.

FIG. 9 shows the release lever 112. In this exemplary embodiment, itincludes a locking bar 320 extending between, and integrally formedwith, grips 322. A pin receiving hole 324 in the grips 322 receives thepin 126 (FIG. 5), which extends parallel to the locking bar 320. The pin126 also passes through the pivot portion 250 and the torsion spring 124to pivotally secure the release lever 112 in place on the inner jaw 108.

As shown in FIG. 9 and in the cross sectional view of FIG. 4, thelocking bar 320 includes a generally irregular quadrilateralcross-sectional shape, but also includes mild concave and convex curves.The curves may be concentric about a pivot axis formed by the pin 126and the pin receiving holes 324. Accordingly, the curved surface may beconcentric with the outer surface of the cylindrical pin 126.

The locking bar 320 may interface with the locking interface 290 on theouter jaw 110 to place the outer jaw 110 in the provisionally lockedcondition. Likewise, when pivoted about the pin 126, the locking bar 320may interface with the rear end 274 of the outer jaw 110 to permit theouter jaw 110 to rest in the opened bar-receiving position.

Centrally disposed in the curved surface of the locking bar 320 is acutout 324 facing the pin-receiving holes 324. This cutout 324 is sizedto receive the torsion spring 124 as it extends about the pin 126. Thetorsion spring 124 applies a biasing force on the release lever 112 toplace the release lever 112 in the provisionally locked position.

The grips 322 are ergonomically shaped for easy grasping with a thumband forefinger. These are generally triangularly shaped and includeprotruding edges permitting a surgeon to grasp the release lever 112with two fingers to pivot the release lever about the pin so that theouter jaw 110 moves to the open, bar-receiving position.

FIGS. 10A-C show the top clamp 102 in the open position, during barinsertion, and in the closed position, respectively. Referring first toFIG. 10A, in the open position, the release lever 112 is pivoted aboutthe pivot connection so that the locking bar 320 lies behind the rearend 274 of the outer jaw 110.

In use, a surgeon may place the clamping device 100 in the open positionby grasping the release lever 112 between his thumb and forefinger andpivoting the release lever 112 about the pin 126 to overcome the forceof the biasing torsion spring 124. Once sufficiently drawn back, thewire spring (not shown in FIG. 10A) biases the outer jaw 110 to pivotabout the spherical washer 116 to an open position, separating the outerjaw and inner jaw hook portions 282, 256. Accordingly, the shape andloading articulates the top jaw 110 to open the front end of the clamp102. Accordingly, here, the device 100 is in a cocked position.

FIG. 10B shows a bar 260 being inserted between the inner and outer jaws108, 110. As the bar contacts the rearward portion of the transversegroove 280 of the outer jaw 110, the outer jaw 110 is forced rearwardly.This rearward movement pivots the outer jaw about the spherical washer116 enough to raise the rear end of the outer jaw 110 above the lockingbar 320. Once this occurs, the biasing force of the torsion spring 124pivots the release lever 112 so that the locking bar 320 acts againstthe locking interface surface 290 of the outer jaw 110. The torsionspring force overcomes the biasing force of the wire springs and as therelease lever 112 continues to pivot, the locking bar 320 continues toforce the outer jaw 110 further closed, thereby snapping shut to gripthe bar 260.

FIG. 10C shows the clamp 102 in the provisionally closed position. Inthis position, the bar 260 is provisionally secured within the clamp 102between the outer and inner jaws 110, 108. In this position, the bar 260may be rotated within the clamp 102 or the clamp may be rotated aboutthe bar, the clamp 102 may be slid along the bar 260, and the outer andinner jaws 110, 108 may be pivoted relative to the saddle base 106 androtated about the binding post 114. Thus, the clamp 102 snaps onto a barbut permits continued adjustment as the surgeon finishes locating thepins or building the frame.

Once the pins and bars are in a desired position, and with reference toFIG. 4, the surgeon locks the clamp 102 against further movement bytightening one or both of the nuts 118 on the binding post 114. Asdiscussed above, the use of a collar or snap ring on the binding post114 may allow independent locking of both clamps 102, 104. Thiscompresses the wave spring 120 and the radially extending splines in theopposing saddle bases 106 engage each other. This also meshes thesplines on the inner jaw 108 and the concave side of the saddle base106, as well as drives the spherical washer 116 tight against the outerjaw 110. The outer jaw 110 then is forced against the inner jaw 108 andthe release lever 112 to more tightly secure the bar in place betweenthe jaws. Thus, in a fully locked state, the clamping device 100 islocked against all relative movement of the clamps, including releasingthe bar.

To release the bar, the surgeon performs the steps in reverse.Particularly, he first loosens the nuts, placing the clamping device 100in the provisionally locked state. Then he may grasp and rotate therelease lever 112 so that the locking bar 320 is out of engagement withthe outer jaw 110. The outer jaw 110 will open and the bar may beremoved. Or course, if the clamps 102, 104 are independent lockable,such as when a snap ring or collar is incorporated into the binding post114, then the clamps may be locked or released independently.

FIGS. 11-15 show another embodiment of a clamping device, referred toherein as 400. The device 400 is a low-profile clamping device that,like the device 100 discussed above, minimizes the pin to bar centerlinedistance. Large centerline distances increase the working envelope andincrease the moment arm of the clamping device, subjecting the clampingdevice to increased moment loading necessitating a larger device. Thedevices shown herein, including the exemplary device in FIGS. 11-15,minimizes the pin to bar centerline distance by replacing the ball jointwith two cylindrical surfaces on the inner jaw halves (one for eachclamp half) and retaining a revolute joint between the two clampassemblies so that it achieves the roll, pitch and yaw of a ball jointwhile also adding two additional degrees a freedom, namely the abilityfor the jaw halves to translate along the cylinder axes allowing forgreater ease of assembly, fracture reduction, and load sharing whilemaintaining a close pin to bar centerline distance resulting in a morecompact, lower loaded device.

Added degrees of freedom can be appreciated by considering a simplysupported beam. A beam with two simple supports can be described andanalyzed with simple means; however skeletal fixation does not rely onsimple supports but rather fixed ones. In this condition a misalignmentor variations in stiffness of one support relative to the other resultsin an unequal sharing of the loads, or rather, an indeterminate problem.This is further complicated by the fact that at a minimum there aretypically at least four pins for each bar, if the pins are consideredthe supports and the bar the beam it can be readily appreciated whyadditional degrees of freedom are advantageous.

Turning now to FIG. 11, the exemplary clamping device 400 includes botha top clamp 402 as a bar clamp and a bottom clamp 404 as a pin clamp. Insome embodiments, the top and bottom clamps 402, 404 each operate in anidentical manner and differ only in the size of the cylinder that thepin and bar clamp can accommodate. Like the top and bottom clamps 102,104 discussed above, the clamp pair 402, 404 can be used to fixate pinsto pins, pins to bars, or bars to bars or a single clamp can be used tofixate either a pin or a bar to some other apparatus such as a ring ormonolateral external fixation and/or deformity correction device. Theclamp mechanism whether used singly or in pairs operates the same aseach half is independent of one another.

FIG. 11 shows the top clamp 402 in cross-section and the clamp 404 as asolid view. Each clamp 402, 404 includes a saddle base 406, an inner jaw408, an outer jaw 410, and a release slide 412. These are connectedtogether by a binding post 414, a compression sleeve 416, and atightening nut 418. The inner and outer jaw 408, 410 cooperate to forman opening 420 for receiving a bar therein.

Each clamp 402, 404 of the clamping device 400 provides multiple degreesof freedom. FIG. 11 shows the degrees of freedom as a roll axis 422, apitch axis 424, and a yaw axis 426 in the upper clamp 402. The roll axis422 is the axis of a bar within the clamp 402 and about which theclamping device 400 rotates. The pitch axis 424 is the axis about whichthe outer and inner jaws 410, 408 rotate relative to the saddle base 406and relative to the lower clamp 404. The yaw axis 426 is defined by thebinding post 414 and about which one of clamps 402, 404 can rotaterelative to the other. As can be seen in FIG. 4, the two pitch axes 152are offset from each other and lie in parallel planes. Offsetting theaxes in this way assists in lowering the overall profile of the device100. In some embodiments, these may be offset a distance within therange of about 0.2 inch or greater. Other embodiments may have the axesoffset more than 0.5 inch. Yet others have the axes offset more or lessthan these exemplary distances.

The binding post 414 secures the top and bottom clumps 402, 404together, or in other embodiments, secures one of the clamps to anotherfixation or other device. The view in FIG. 11 shows only one half of thebinding post 414, as the other half extends into the bottom clamp 404.The binding post axis corresponds to the yaw axis 426, about which theclamps 402, 404 can rotate relative to each other and relative to thebinding post 414.

At its upper end, the binding post 414 includes a spherical ball joint415. The center of this spherical joint 415 coincides with both the yawaxis 426 and the pitch axis 424 of the cylindrical surface of the base406 described below. This relationship allows the clamp 402, as well asany pin or bar contained within the clamp 402 to pivot about its centerand rotate about the pitch axis 424.

The base 406 a of the upper clamp 402 includes a concave saddle portion428 that interfaces with the lower outer surface 430 the inner jaw 408.The concave saddle portion 428 has an axis corresponding to the pitchaxis 424, and about which the inner jaw 408, the outer jaw 410, and therelease slide 412 can rotate.

Like the exemplary clamping device 100 discussed above, the base 406 ahas a circular array of radial splines on its bottom surface 432 thatact to mate with radial splines on the corresponding base 406 b on thelower clamp assembly 404 or some other foundation if used individually.Similar to those splines described above, the splines resemble those ona poker chip and provide positive retention from planar rotation whenthe bottom surfaces 432 are clamped together. The concave saddle portion428 side of the base 406 a is a cylindrical surface which in someembodiments, has a series of longitudinal splines as shown and discussedabove with reference to the clamping device 100. These longitudinalsplines mate to similar splines on the bottom surface 430 of the innerjaw 408 and act to provide positive rotation retention when in theclamped or locked state.

The lower or inner jaw 408 is cylindrically shaped on its lower surface430 and includes longitudinal splines that interdigitate with those onthe base 406 a when in the clamped state. The longitudinal splines maybe similar to those shown in and described with reference to FIGS. 7A,7C and 7D. A transverse groove formed in the inner jaw 408 in partcreates the opening 420 that accepts the pin or bar. In addition, theinner jaw 408 includes a central clearance bore 434 or hole throughwhich the binding post extends. This central bore 434 is sized andconfigured to provide clearance to the binding post 414 that allows forboth rotation about the pitch axis 424 in the amount of, for example,+/−20 degrees as well as axial translation along the pitch axis 424 asindicated by the arrow shown. The amount of axial translation may belimited by the size of the binding post and the size of the central bore434. In some embodiments, the permitted axial translation is within arange of 0.1 to 1 inch. When both clamps 402, 402 translate, the totalamount of translation for the device 400 can be up to double this range.

A hinge pin 436 connects the inner jaw 408 and the outer jaw 410. In theembodiment shown, the inner jaw 408 includes a recess into which aportion of the outer jaw extends. The hinge pin 436 passes through boththe inner jaw and the outer jaw providing a pivot hinge connection thatpermits the outer and inner jaws 408, 410 to be opened and closed toachieve sufficient clearance at the opening 420 to receive a bar or pin.

Like the inner jaw 408, the outer jaw 410 half has a transverse cut (notshown) that accepts the pin or bar. The outer jaw includes a dovetailslot 430 that accepts the release slide 412, and allows it to sliderelative to the outer jaw 410.

The release slide 412 cooperates with the outer jaw 410 to either openor close the opening 430. It has a corresponding dovetail feature 440which mates with the dovetail slot on the outer jaw 410. Because thisdovetail slot 438 on the outer jaw 410 is on a slope, when the releaseslide 412 is slid rearward it also moves downward, removing theconstraint on the outer jaw 410 and allowing the outer jaw 410 to openin order to accept the pin or bar. Once the release slide 412 is slidback up the ramp it acts as a door stop in preventing the outer jaw 410from opening up, preventing the inadvertent release of the pin or bar.Some embodiments include a compression spring or other biasing memberthat biases the release slide 412 into the upper locked position.

FIG. 16 for example, shows a partial cross-sectional view of the clamp402 with an exemplary biasing member 444 that applies loading to biasthe release slide 412 into the locked position. Here, the biasing memberis disposed half in the upper jaw 410 and half in the release slide 412.Although shown as a coil spring, other biasing members are contemplated.

Referring to FIG. 11, one or more guide pins 442 extends through therelease slide 412 and across the central clearance bore 434. As shown inFIG. 14, these guide pins 442 may be introduced through a rear portionof the release lever. The guide pins pass through receiving bores (notshown) on compression sleeve 416 securing the compression sleeve to therelease slide 412. During translation as well as during actuation of therelease lever, the guide pines 412 slide relative to the compressionsleeve 416.

In another exemplary embodiment, instead of employing guide pins tosecure the compression sleeve in the bore of the release slide, thecompression sleeve itself includes extending protrusions that fit intoand slide within guide slots formed inside the release slide bore. Oneexemplary embodiment of such a compression sleeve 450 is shown in FIG.15. The compression sleeve 450 includes wings 452 protruding fromopposing sides that fit within a guide slot formed in the bore sidewallof the release slide 412, securing the compression sleeve 416 to therelease slide 412. The wings allow the compression sleeve 416 to slidefront to back with respect to the release slide 412, but does not allowit to move up and down relative to the release slide 412. On the innercylindrical bore is a left hand helical thread that engages with thetightening nut 418.

The tightening nut 418 engages with the compression sleeve 416 on itsouter threaded cylindrical surface. It includes at its lower end aspherical joint that mates with the binding post 414, through its centeris a broached hexagonal hole that accepts a tool for tightening.

In use, a surgeon may slide back the release slide 412 relative to theouter jaw 410. This opens the outer jaw 410 relative to the inner jaw408. Once a bar or pin is in the transverse cuts between the outer andinner jaws 410, 408, the release slide 412 may be either moved, orsnapped back toward the front of outer jaw 410. This closes the jawpositively retaining the pin or bar from detachment but not firmlyfixating it. Accordingly this is a provisionally locked position,allowing the pin or bar to move in accordance with the degrees offreedom of the clamping device 400.

Tightening the tightening nut 418 provides a clamping force between thebinding post 414 and the release slide 412 effectively clamping togetherthe base 406, the outer and inner jaws 408, 410, and the release slide412, and applying pressure to the pin or bar in the clamp. Because ofthe slight slope between the outer jaw 410 and the release slide 412,the release slide 412 acts as a door stop on the outer jaw 410. Thus,the greater the clamping force the greater the resistance to slidingthus preventing the jaws from opening. Releasing the pin may beaccomplished by reversing the steps.

In some aspects this disclosure is directed to an exemplary clampingdevice for an external fixation system. The device includes a firstclamping system connected to a second clamping system by a saddleassembly. The saddle assembly includes first and second outwardly facingconcave surfaces that respectively interface with the first and secondclamping systems. The first and second outwardly facing concave surfaceshave a respective first and a second pitch axis. The first clampingsystem is moveable relative to saddle assembly to pivot within a rangeof more than 20 degrees about the first pitch axis and the secondclamping system moveable relative to saddle assembly to pivot within arange of more than 20 degrees about the second pitch axis. In someexamples, the first and second pitch axes are offset by more than 0.5inch. In some examples, the first and second pitch axes lie in parallelplanes. In some examples, the first and second clamping system arerespectively moveable relative to saddle assembly to pivot within arange of 40 degrees or more about the first and second pitch axes,respectively.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions andalterations herein without departing from the spirit and scope of thepresent disclosure.

I claim:
 1. A clamping device for an external fixation system,comprising: a post component having a yaw axis; a first outer jaw; afirst inner jaw having an inner surface facing the outer jaw, the outerand inner jaws secured to the post component and rotatable about the yawaxis, and together forming an opening for receiving a first fixationelement along a roll axis approximately perpendicular to the yaw axis;and a trigger system configured to release the first outer and firstinner jaws from a cocked condition corresponding to an openbar-receiving condition to a provisionally locked condition thatcaptures the first fixation element as a result of triggering thetrigger system, the cocked condition being a self-maintained condition.2. The clamping device of claim 1, wherein the trigger system comprisesa release component and a biasing element that biases the releasecomponent toward the provisionally locked condition.
 3. The clampingdevice of claim 2, wherein the release component includes a graspableportion and a transversely extending bar that interfaces with thebiasing element and with one of the first outer and first inner jaws. 4.The clamping device of claim 1, wherein the trigger system comprises arelease component pivotably attached to one of the first inner and firstouter jaws, the release component slidingly engaging the other of thefirst inner and first outer jaws in a manner that biases said one of thefirst inner and first outer jaws to the provisionally locked condition.5. The clamping device of claim 1, including a tightening componentconfigured in a manner that an action of tightening the tighteningcomponent locks the jaws in a locked condition.
 6. The clamping deviceof claim 1, wherein the first outer and first inner jaws are movablebetween an open bar-receiving position and a clamped, closed-position,the clamping device further comprising a bias member biasing the firstouter and first inner jaw to an open bar-receiving position.
 7. Aclamping device for an external fixation system, comprising: a firstclamp comprising: a first outer jaw; a first inner jaw having an innersurface facing the outer jaw, the outer and inner jaws together formingan opening for receiving a first fixation element of the externalfixation system; and a first trigger system configured to release thefirst outer and first inner jaws from a cocked condition correspondingto an open bar-receiving condition to a provisionally locked condition,the cocked condition being a self-maintained condition; and a secondclamp coupled to the first clamp, the coupled first and second clampsbeing configured to maintain the first fixation element and a secondfixation element of the external fixation system in a position relativeto each other, the second clamp comprising: a second outer jaw; a secondinner jaw having an inner surface facing the second outer jaw, thesecond outer and second inner jaws together forming an opening forreceiving the second fixation element of the external fixation system;and a second trigger system that releases the second outer and secondinner jaw from an open bar-receiving condition to a provisionally lockedcondition.
 8. The clamping device of claim 7, including a tighteningcomponent configured in a manner that an action of tightening thetightening component simultaneously locks a) the first outer and firstinner jaws and b) the second outer and second inner jaws.
 9. Theclamping device of claim 7, comprising: a first tightening componentassociated with at least one of the first inner and first outer jaws;and a second tightening component associated with at least one of thesecond inner and second outer jaws, wherein each of the first and secondtightening components are configured in a manner that an action oftightening one of the tightening components simultaneously locks a) thefirst outer and first inner jaws and b) the second outer and secondinner jaws.
 10. A clamping device for connecting external fixationelements of an external fixation system, comprising: a first fixationclamp, comprising: a first jaw having a jaw hook; a second jaw disposedin a cooperating relationship with the first jaw, the first and secondjaws together forming an opening between the jaw hook and the secondjaw, the first and second jaws being displaceable relative to oneanother between an open position where the opening between the jaw hookand the second jaw is sized to receive a first fixation element of theexternal fixation system and a closed position where the opening betweenthe jaw hook and the second jaw is sized to secure the first fixationelement of the external fixation system; a biasing element configured toact on at least one of the first and second jaws to bias the first andsecond jaws together to the open position; and a trigger system moveablebetween an open position and a closed position, wherein, when thetrigger system is in the open position, the opening between the jaw hookand the second jaw is expandable to receive the first fixation elementof the external fixation system, and when the trigger system is in theclosed position, at least a portion of the trigger system mechanicallyinterferes with the displacement of the first and second jaws preventingthe first and second jaws from displacing to the open position.
 11. Theclamping device of claim 10, wherein the at least a portion of thetrigger system that mechanically interferes with the displacement of thefirst and second jaws is disposed between the first and second jaws whenthe trigger system is in the closed position.
 12. The clamping device ofclaim 10, wherein the trigger system is configured to snap between theopen position to the closed position upon displacement of one of thefirst and second jaws relative to the other of the first and secondjaws.
 13. The clamping device of claim 10, wherein the at least aportion of the trigger system that mechanically interferes with thedisplacement of the first and second jaws is a blocking component thatdisplaces relative to the first and second jaws from a position disposedbetween the first and second jaws when in the closed position to aposition not between the first and second jaws when in the openposition.
 14. The clamping device of claim 10, wherein the biasingelement is disposed to act directly against one of the first and secondjaws.
 15. The clamping device of claim 10, wherein the first fixationclamp is configured to receive the first fixation element at a firstend, and the trigger system is disposed to cooperate with at least oneof the first and second jaws at a second end opposite the first end. 16.The clamping device of claim 10, comprising: a second fixation clamp,comprising: a third jaw; a fourth jaw disposed in a cooperatingrelationship with the third jaw, the third and fourth jaws togetherforming an opening configured to receive a second fixation element ofthe external fixation system.
 17. The clamping device of claim 16,including a tightening component configured in a manner that an actionof tightening the tightening component simultaneously locks a) the firstand second jaws and b) the third and fourth jaws.
 18. A clamping devicefor connecting external fixation elements of an external fixationsystem, comprising: a post component having a yaw axis; a first fixationclamp secured to the post component and rotatable about the yaw axis,the first fixation clamp comprising: a first jaw having a jaw hook; asecond jaw disposed in a cooperating relationship with the first jaw,the first and second jaws together forming an opening between the jawhook and the second jaw, the first and second jaws being displaceablerelative to one another between an open position where the openingbetween the jaw hook and the second jaw is sized to receive a firstfixation element of the external fixation system and a closed positionwhere the opening between the jaw hook and the second jaw is sized tosecure the first fixation element along a roll axis approximatelyperpendicular to the yaw axis; a biasing element disposed and configuredto act on at least one of the first and second jaws to bias the jaw hookand the second jaw in a direction away from each other; and a triggersystem configured to release the first outer and first inner jaws fromthe open position to the closed position.
 19. The clamping device ofclaim 18, wherein when the trigger system is in the open position, theopening between the jaw hook and the second jaw is expandable to receivethe first fixation element of the external fixation system, and when thetrigger system is in the closed position, at least a portion of thetrigger system mechanically interferes with the displacement of thefirst and second jaws preventing the first and second jaws fromdisplacing to the open position.
 20. The clamping device of claim 19,wherein the at least a portion of the trigger system that mechanicallyinterferes with the displacement of the first and second jaws isdisposed between the first and second jaws when the trigger system is inthe closed position.
 21. The clamping device of claim 18, wherein the atleast a portion of the trigger system that mechanically interferes withthe displacement of the first and second jaws is a blocking componentthat displaces relative to the first and second jaws from a positiondisposed between the first and second jaws when in the closed positionto a position not between the first and second jaws when in the openposition.
 22. A clamping device for an external fixation system,comprising: a post component having a yaw axis; a first outer jaw; afirst inner jaw having an inner surface facing the outer jaw, the outerand inner jaws secured to the post component and rotatable about the yawaxis, and together forming an opening for receiving a first fixationelement along a roll axis approximately perpendicular to the yaw axis;and a trigger system configured to release the first outer and firstinner jaws from an open bar-receiving condition to a provisionallylocked condition that captures the first fixation element as a result oftriggering the trigger system, wherein the trigger system comprises arelease component and a biasing element that biases the releasecomponent toward the provisionally locked condition.